Moses Mendelssohn

Moses Mendelssohn (b. 1729, d. 1786) was a creative and eclectic
thinker whose writings on metaphysics and aesthetics, political theory
and theology, together with his Jewish heritage, placed him at the
focal point of the German Enlightenment for over three decades. While
Mendelssohn found himself at home with a metaphysics derived from
writings of Leibniz, Wolff, and Baumgarten, he was also one of his
age's most accomplished literary critics. His highly regarded pieces on
works of Homer and Aesop, Pope and Burke, Maupertuis and Rousseau
— to cite only a fraction of his numerous critical essays —
appeared in a series of journals that he co-edited with G. E. Lessing
and Friedrich Nicolai. Dubbed “the Jewish Luther,” Mendelssohn also
contributed significantly to the life of the Jewish community and
letters in Germany, campaigning for Jews' civil rights and translating
the Pentateuch and the Psalms into German. Not surprisingly, as a Jew
with an unwavering belief in the harmonizing effects of rational
analysis and discourse, Mendelssohn rankled both institutional and
self-appointed advocates of Christianity as well as Judaism. Thus,
Johann Lavater infamously challenged him to refute the arguments of the
Pietist theologian, Charles Bonnet, or convert to Christianity (a
challenge that Mendelssohn effectively disabled with a plea for
tolerance and a series of reasons for refraining from such religious
controversy). Similarly, some Jewish thinkers took exception to
Mendelssohn's Jerusalem, or on Religious Power and Judaism and
its argument for conceiving Judaism as a religion founded upon reason
alone. In addition to the “Lavater affair” and his work as editor and
critic, Mendelssohn was probably best known to his contemporaries for
his penetrating accounts of the experience of the sublime, for lucid
arguments for the soul's immortality and God's existence, for his close
association with G. E. Lessing, for his protracted “pantheism
dispute” (Pantheismusstreit) with Jacobi during the 1780s, and for
his insistence that Lessing was not the Spinozist that Jacobi portrayed
him to be. To posterity he is perhaps best known as the model for
Nathan der Weise, the protagonist in Lessing's famous play of
the same name, championing religious tolerance.

Mendelssohn's “On Evidence in Metaphysical Sciences” (the so-called
Prize Essay) garnered first prize in the contest staged by the
Royal Prussian Academy of Sciences on the question of whether
metaphysical truths are able to have the same sort of evidence as
mathematical truths. (An essay by Immanuel Kant came in second place.)
In the essay, published in 1763, Mendelssohn argues that metaphysics
pursues its subject matter by applying the same method that mathematics
does: conceptual analysis. As he puts it, “The analysis of concepts is
for the understanding nothing more than what the magnifying glass is
for sight” (Philosophical Writings, p. 258). But Mendelssohn
then proceeds to differentiate the kinds of evidence in mathematics and
in metaphysics in the following way. Like calculus, but unlike
geometry, metaphysics works with concepts that are no less certain than
those of geometry, but lack the transparency and imaginative resources
available to the geometer's concepts. The difference between
mathematics and metaphysics lies in the difference in the content of
the concepts, namely, the difference between quantity and quality. At
the same time, there is a basic harmony between the two disciplines
since quantity and quality are both intrinsic characteristics of finite
things and neither quantity nor quality exists without the other
(though qualities and not quantities are allegedly conceivable without
some other thing).

Mendelssohn acknowledges that, despite the fact that the method is
the same and the content in each case (mathematics and metaphysics) is
an intrinsic character of things, progress in metaphysics has lagged
far behind that in mathematics. He suggests three “objective” reasons
for this lag: first, metaphysics' greater reliance upon arbitrary signs
(signs that do not essentially coincide with what is signified);
second, the holistic content of metaphysics (no quality can be defined
without an adequate insight into the others); and third, metaphysics'
need to establish the actual existence of what corresponds to the
analyzed concepts. Thus, for Mendelssohn, mathematical truths need not
suppose more than the appearances of things as long as a distinction is
maintained between constant and inconstant appearances or,
equivalently, between appearances that have their basis in the
intrinsic, essential constitution of our senses and those that do not
(e.g., those due to sickness or a faulty perspective). “Thus, even in
the system of a doubter or an idealist, the value of not only pure,
theoretical mathematics but even practical and applied mathematics
remains, and it retains its undeniable certainty” (Philosophical
Writings, p. 268). Metaphysics, by contrast, requires a resolution
of the problem of idealism.

Twenty-five years after the Prize Essay, Mendelssohn
continues to struggle with the issue of idealism in Morning
Hours, his final metaphysical work. Although he espouses a theism
that is compatible with a realist position (what he dubs
“dualism” as opposed to idealism, materialism, and
skepticism), he appears to be moving toward a position that straddles
an idealist/non-idealist divide. He views inquiry into something
“extra-conceptual” as tantamount to “inquiring about
a concept that is actually no concept and therefore something
contradictory is supposed” (Morning Hours,
p. 42/Gesammelte Schriften, 3/2, pp. 60f). A further tilt in
the direction of idealism is apparent in his rejection of the
traditional definition of truth as an agreement of things with
thoughts, on the ground that the copy (the thought) cannot be compared
with the original (the thing). Since thoughts can be compared with one
another, he turns to them for a determination of truth, though it is
not clear how this move can avoid idealism. At the same time, however,
he distinguishes truths that are certain (consisting in the
agreement of thoughts with themselves) from actual truths,
determined by adherence to principles of induction and analogy in
addition to the principle of noncontradiction. The latter truths are
truths about facts outside us or about a causal connection, though
they are relative to certain factors: the number of sensations of a
single sort that agree with one another, the number of different sorts
of sensations that concur, and the number of times our assessment
agrees with those of others, of other species, and of even
“higher entities” (Morning Hours, pp. 6f, 37ff,
41/Gesammelte Schriften, 3/2, pp. 15f, 54f, 59). Echoing
Descartes, Mendelssohn maintains that demonstration of God's existence
is necessary to certify the actual existence of things outside us.

This ambivalence can perhaps be traced to the mature Mendelssohn's
growing suspicions that the entire issue separating idealists and
those supporting contrasting positions is misbegotten, a product of
linguistic confusion (see the discussion of Mendelssohn's views on
language below). “I fear that, in the end, the famous debate
among materialists, idealists, and dualists amounts to a merely verbal
dispute that is more a matter for the linguist than for the
speculative philosopher” (Morning Hours, p. 42
(translation slightly altered)/Gesammelte Schriften, 3/2,
p. 61). Mention has already been made of Mendelssohn's view in
the Prize Essay that metaphysics' necessary reliance upon
artificial signs is one reason why its difficulties are more
intractable than those of mathematics. In 1785, in Morning
Hours, he goes further: “You know how much I am inclined to
explain all the controversies of the philosophical schools as merely
verbal disputes or at least as originally deriving from verbal
disputes” (Morning Hours, p. 75/Gesammelte
Schriften, 3/2, p. 104; see Dahlstrom (2011)). In keeping with
these advancing suspicions about the origin and the efficacy of the
issue over idealism and dualism (realism), Mendelssohn eventually
comes to assign reason a mediating role in disputes between common
sense and speculation. Common sense is usually but not invariably
right, he contends, and hence reason's task is to present a defense of
speculation when it departs from common sense. (This appeal to reason
to mediate and, if necessary, to rein in speculation also plays a
significant role in Mendelssohn's account of a “refined”
or “purified” pantheism in Morning Hours. On
this point, see below “8. Controversy with Jacobi over Lessing's
alleged pantheism”).

In Phaedo or On the Immortality of the Soul, loosely modeled
on Plato's dialogue, Mendelssohn combines a paean to Socrates with an
elaboration of the dreadful personal, moral, and political
implications if a person's life is her “highest good.” A
best-seller of its time, running through three editions, this
“classic of rational psychology,” as Dilthey put it, also
contains an argument for the simplicity and immortality of the human
soul, explicitly singled out for criticism by Kant in the second
edition of the Critique of Pure Reason. Mendelssohn supports
the notion that the soul is simple and thus indestructible by noting
that certain features of the soul, namely, the unifying character of
consciousness and the identity of self-consciousness, cannot be
derived from anything composite, whether those composite parts be
capable or not of thinking. “We would be able neither to
remember nor to reflect nor to compare nor to think, indeed, we would
not even be the person who we were a moment ago, if our concepts were
divided among many and were not to be encountered somewhere together,
combined in the most precise ways they can. We must, therefore, assume
at least one substance that combines all concepts of the component
parts…. There is, therefore, in our body at least one sole
substance that is not extended, not composed, but instead is simple,
has a power of presentation, and unites all our concepts, desires, and
inclinations in itself” (Phädon (2007), pp. 119f
(translation slightly altered)/Gesammelte Schriften, 3/1,
pp. 96f). As for the human soul's fate after death, Mendelssohn
appeals to divine goodness and providence, which perhaps explains why,
following the publication of the
Phaedo, he finds himself needing to revisit the proofs for
God's existence.

From the beginning of his career to the end, Mendelssohn
consistently upheld the demonstrability of God's existence. However,
not all arguments were equally compelling in his view. In the Prize
Essay he contends that probable arguments for God's existence
based upon beauty, order, and design are more eloquent and edifying but
less certain and convincing than strict demonstrations. Similarly, in
Morning Hours, he cites the argument that the external senses'
testimony to an external world is unthinkable without a necessary,
extra-worldly being, but adds that this sort of argument would hardly
convince an idealist, sceptic, or solipsist. There are, however, at
least two ways in which, according to Mendelssohn, God's existence can
be established with certainty. The first way is through application of
the principle of sufficient reason to the certain existence of
contingent things. The inner testimony of one's own cogito attests to
the existence of something contingent. Since the sufficient reason for
the existence of contingent things must “indirectly” be a necessary
being, a necessary being exists. Hence, Mendelssohn sums up this
argument by saying: “I am, therefore there is a God.”
(Philosophical Writings, p. 289; Gesammelte
Schriften, 3/2, pp. 78, 83f).

Mendelssohn's second way of proving God's existence is based upon
consideration of the idea of God together with the conditions of
nonexistence. If something does not exist, then it is either
impossible or merely possible. To say that something nonexistent is
impossible is to say that its intrinsic properties are contradictory,
e.g., a square circle. To say that something nonexistent is possible
is to say both that its intrinsic properties are insufficient to
determine that it exists and that it is contingent upon extrinsic
factors that do not obtain. If God does not exist, then it is either
because the idea of God is impossible or because it is merely
possible, i.e., contingent. Since contingency entails dependency and
independence is greater than dependence, it would contradict the
essence of a perfect being for that being to be contingent. Hence, the
idea of a perfect being cannot be the idea of something merely
possible. But the idea of a perfect being also does not contain
determinations that must be affirmed and denied at the same time; in
other words, the idea is not impossible. In this way Mendelssohn
concludes that God exists from the consideration that the idea of God
cannot be the idea of something nonexistent. While we can conceive
finite, contingent, entities as nonexistent, we cannot conceive as
nonexistent an infinite, necessary entity, namely, an entity that
combines all affirmative features and properties to the highest
degree. “It can either not be thought at all or not be thought
otherwise than with the predicate of actual existence”
(Morning Hours, p. 113/Gesammelte Schriften, 3/2,
p. 154). In this connection, it deserves mention that Mendelsson
rejects as quibbling the objection that existence is not a
predicate. A concept of existence, he maintains, emerges in all of us
in a similar way as we search for what is common to what we do and
undergo, thereby enjoying a universality that is not further
analyzable. Thus, Mendelssohn will allow that existence is not a
predicate, that it is different from all features and properties of
things, and, hence, cannot be merely added to the list of properties
of the most perfect entity. Nevertheless, whether existence is the
“position” of all properties of a thing or something
inexplicable, Mendelssohn stands by his claim that we can only think
something contingent without it. As he sums up the inference: “A
God is thinkable, therefore a God is also actually on hand
[vorhanden]” (Morning Hours, p. 56
(translation slightly altered)/Gesammelte Schriften, 3/2,
p. 78).

Towards the end of Morning Hours Mendelssohn introduces a
further proof for God's existence, based upon our certainty of
“the imperfection of our self-knowledge” (Morning
Hours, p. 107/Gesammelte Schriften 3/2, p. 147). We
have certain knowledge, Mendelssohn contends, not only of ourselves
but also of the limited scope of this knowledge. “I am not
merely what I distinctly know of myself or, what amounts to the same,
there is more to my existence than I might consciously observe of
myself; and even what I know of myself is in and for itself capable of
far greater development, greater distinctness, and greater
completeness than I am able to give it” (Morning Hours,
p. 103/Gesammelte Schriften 3/2, p. 141). From the
limitations of our knowledge of ourselves (or, for that matter, of
anything actual existing) together with the less plausible assumption
that “that everything actual must be thought to be actual by
some thinking being,” Mendelssohn infers that there is “an
infinite intellect” that does represent everything to itself
(Morning Hours, pp. 103f/Gesammelte Schriften 3/2,
pp. 141ff).

In On the Main Principles of the Fine Arts and Sciences,
Mendelssohn sets out from the assumption that the human spirit has
learned to imitate beauty, “the self-empowered mistress of all our
sentiments,” in works of art. He then proceeds to ask what the arts
have in common or, in other words, what beauty is. Batteux's thesis
that art consists in the imitation of nature merely defers the question
or, better, requires its revision to the effect that we ask what the
beauties of nature and of art have in common. After rejecting
Hutcheson's appeal to an aesthetic sense as a deus ex machina that
forecloses inquiry, Mendelssohn contends that the common feature is a
sensuously perfect representation (a contention that can be traced back
to Sulzer and Baumgarten). “Sensuous” in this connection stands not
simply for the fact that an object is sensed by the external senses,
but also for the fact that an entire array of an object's features is
perceived all at once. Unlike the distinct representation of a triangle
whereby the intellect distinguishes parts and aspects of the triangle
from one another, a sensuous representation is clear but indistinct,
that is to say, to have a sensuous representation is to perceive
something without intellectually distinguishing its parts or aspects.
But we can sensuously perceive an order or harmony to those aspects
without intellectually distinguishing them. Beauty or the perfect
sensuous representation — whether in nature or in art —
accordingly pertains to forms, orders, harmonies, and “indeed,
everything capable of being represented to the senses as a perfection”
(Philosophical Writings, p. 172). On this definition of art,
what is represented can be ugly or repugnant as long as the
representation is sensuously perfect (though Mendelssohn does address,
as discussed below, the mixed sentiment that accrues when the object
represented is unpleasant). From these considerations, Mendelssohn
derives two necessary conditions of fine art and letters: faithfulness
of the representation (“imitation”) and, far more importantly, the
artistry, even “genius,” involved. In this connection, he argues that,
as far as individual beauties in nature are concerned, they are
inferior to the beauties produced by arts. In On the Main
Principles Mendelssohn also establishes the general distinction
between fine arts and fine science along the lines of the difference
between natural and artificial signs. Whereas the “fine arts”
(beaux arts) — music, dance, painting, sculpture, and
architecture — predominantly work with natural signs, the “fine
sciences” (belles lettres) — poetry and rhetoric —
typically employ artificial signs. The distinction is hardly ironclad,
however, and Mendelssohn ends On the Main Principles with a
discussion of ways the arts may borrow from one another (e.g.,
allegorical painting) or combine (e.g., opera).

At one point in the dialogue On Sentiments (Mendelssohn's
second publication but first publication on aesthetic matters), one of
the protagonists differentiates three sorts of pleasure: sensuous,
beautiful, and intellectual (a differentiation which approximates
respectively the three sorts of perceptions elaborated by Leibniz and
Wolff, among others, namely, confused, clear, and distinct). In this
context, Mendelssohn explains how beauty affords a distinctive pleasure
precisely as the unity of the multiplicity of things taken in by the
senses (a view subsequently iterated, as we have seen, in On the
Main Principles). Unaddressed by this differentiation of
pleasures, however, are the so-called “mixed sentiments” that we seem
to experience sometimes in viewing what is otherwise painful,
terrifying, or, at any rate, does not exhibit the harmony or order
typical of beauty. At first (namely, in On Sentiments)
Mendelssohn thought that problem could still be handled by identifying
some perfection in the object — e.g., the skillfulness of the
gladiator, the virtue of the tragic figure — as the source of the
pleasure that we feel. Six years later, in Rhapsody or additions to
the Letter on sentiments, he revises his explanation of these
mixed sentiments by noting that each individual representation has a
subjective and an objective component. Subjectively or “as a
determination of the soul,” the representation can affirm some
perfection in the soul and thus be pleasing, even though objectively or
“as a picture of the object,” we might find it repugnant. Tragedy is
more complicated since the sympathy that we feel for the tragic figure
is based upon both objective and subjective perfections (i.e., in him
or her and us) as well as upon objective imperfection, the pain and
injustice that befall him or her.

Mendelssohn gives another twist to his interpretation of “mixed
sentiments” in the Rhapsody and then later in “On the Sublime
and the Naïve in the Fine Sciences.” Experiences of the sheer
immensities of things — “the unfathomable world of the sea, a
far-reaching plain, the innumerable legions of stars, the eternity of
time, every height and depth that exhausts us” (Philosophical
Writings, p. 144) — sometimes make us tremble, but we still
find them alluring. It is gratifying to experience them, though they
confirm an imperfection as well as a perfection in us. In “On the
Sublime,” Mendelssohn further distinguishes beauty as something bounded
from immensity as something unbounded. He then distinguishes extended
from non-extended (intensive) immensity. The sea's unfathomableness
would be an example of extended immensity in nature; uniform repetition
of temporal intervals in music would be an example of an attempt to
represent the experience of an extended immensity in art. But
Mendelssohn seems to be more interested in the non-extended or
intensive immensities. “Power, genius, virtue have their unextended
immensity that likewise arouses a spine-tingling sentiment but has the
advantage of not ending, through tedious uniformity, in satiation and
even disgust, as generally happens in the case of the extended
immensity” (Philosophical Writings, p. 194). Mendelssohn then
introduces the category of sublimity for the perfect representation of
such intensive immensity, a representation that produces awe precisely
because it passes beyond our customary expectations.

There is one last aspect of Mendelssohn's aesthetics that deserves
mention, not least for its bearing on subsequent developments in
aesthetics. It has already been noted that the pleasures of beauty and
sublimity are not to be identified as purely sensuous or purely
intellectual pleasures. In keeping with this differentiation,
Mendelssohn differentiates the sort of approval involved in aesthetic
experiences from knowledge or desire, though he insists that aesthetic
feelings of pleasure can, nonetheless, serve “as the transition
(Uebergang) as it were from knowing to desiring”
(Gesammelte Schriften, 3/2, pp. 61f; Philosophical
Writings, pp. 169, 307–310). In his adoption of three distinct
capacities of the mind and in his appraisal of the aesthetic dimension
as providing a bridge between matters of truth and falsity (capacities
of knowing) and matters of good and evil (capacities of desiring),
Mendelssohn plainly anticipates central aspects of Kant's mature,
critical philosophy. A further, though less precise similarity also
deserves mention, namely, the likeness between Kant's conception of the
disinterested character of experience of the beautiful and
Mendelssohn's conception of the experience as something affording us a
pleasure that is neither simply sensuous or intellectual. “We consider
the beauty of nature and art with pleasure and satisfaction, without
the slightest movement of desire. Instead, it appears to be a
particular mark of beauty that it is considered with tranquil
satisfaction; that it pleases if we also do not possess it and we are
still far removed from demanding to possess it” (Gesammelte
Schriften, 3/2, p. 61; Philosophical Writings, pp.
34–51).

In Jerusalem, or on Religious Power and Judaism Mendelssohn
distinguishes church and state in order to demonstrate the salutary
harmony between them and thus the need for tolerance. In the first part
of the essay he accordingly argues that neither the state nor religion
can legitimately coerce human conscience and, in the second part, he
maintains that this argument against “religious power” is supported by
Judaism. The second point was no less controversial than the first,
especially since many Jewish elders and rabbis maintained a right to
excommunicate. But Mendelssohn counters — apparently erroneously
— that the practice is not inherent in “ancient, original
Judaism” but rather borrowed in the course of time from
Christianity.

Far from separating temporal and spiritual concerns to distinguish
state and church (as Locke did), Mendelssohn insists that “our welfare
in this life is … one and the same as [our] eternal felicity in
the future” (Jerusalem (1983), p. 39). Nor does he base the
distinction between church and state on the difference between
convictions and actions. “Both state and church have as their object
actions as well as convictions, the former insofar as they are based
on the relations between man and nature, the latter insofar as they
are based on the relations between nature and God”
(Jerusalem (1983), p. 56f). As far as convictions are concerned,
neither church nor state can coerce; “for here,” as noted earlier,
“the state has no other means of acting effectively than the church
does. Both must teach, instruct, encourage, motivate”
(Jerusalem (1983), p. 61). What contributes mightily to their
potential for mutual reinforcement is the fact that there is also no
difference in the make-up of the convictions and duties themselves.
The only difference between church and state in the matter of
convictions is their ultimate sanction. Thus, the moral philosopher
will arrive at the same system of duties as the person who sees them
as expressions of the divine; religion “only gives those same duties
and obligations a more exalted sanction” (Jerusalem (1983),
p. 58). Matters are different when it comes to actions where the
state can and must coerce, namely, when society's size and complexity
“make it impossible to govern by convictions alone, [and] the state
will have to resort to public measures, coercive laws, punishments of
crime, and rewards of merit” (Jerusalem (1983), p. 43). Herein lies
for Mendelssohn the basic difference between state and church: civil
society has, as the product of a social contract, the right to
coercion, religious society has no such right. “The state has
physical power and uses it when necessary; the power of
religion is love and beneficence”
(Jerusalem (1983), p. 45).

In Jerusalem, Mendelssohn argues that Judaism is, at
bottom, a natural religion, containing no revealed truths not available
to unaided reason. Occasionally, as Allan Arkush points out
(Jerusalem (1983), p. 20), he speaks more guardedly, restricting this
claim to the “essentials” of Judaism. Even with such qualifications,
however, it is apparent that Mendelssohn approaches Judaism and its
history with a more or less Deist view that the original, ancient faith
confirmed nothing more than rational truths. Nonetheless, he combines
this rationalist approach with a conception of revelation that
underscores the distinctiveness of Judaism and secures Jewish believers
their destiny as God's chosen people. For, while the Sinaitic
revelation contains no supernatural truths, it does prescribe a way of
life, the practice of which stands to benefit all mankind. (The
interpretation of revelation strictly as legislation and not as adding
to the store of truths is very likely borrowed, with qualifications,
from Spinoza). “Judaism boasts of no exclusive revelation of
eternal truths that are indispensable to salvation, of no revealed
religion in the sense in which that term is usually understood.
Revealed religion is one thing, revealed legislation,
another” (Jerusalem (1983), p. 97).

Mendelssohn finds linguistic considerations at the very heart of
traditional philosophical questions. As noted above
(“2. Metaphysics and epistemology”), in the Prize
Essay he regards metaphysics' greater reliance upon arbitrary
signs as one reason for its slow progress (relative to that in
mathematics) and in Morning Hours he indicates his
inclination to regard disputes over idealism as purely verbal.
Joining these remarks about the import of language for philosophy are
two main treatments of language, one at the beginning, the other at
the end of his career. At the outset he critically addresses
Rousseau's views on the origin of language in the context of the
Berlin Academy's essay competitions on language (see Sendschreiben
an den Herrn Magister Lessing in Leipzig, the appendix to the
translation of Rousseau's
Discours sur les origins de l'inégalité (1756),
and Mendelssohn's review of Michaelis’ prize-winning essay
(1759) in Briefe, die neueste Literatur betreffend and
“Über die Sprache” (circa 1759)). Michaelis won the
Academy's prize for answering its question: “Quelle est
l'influence réciproque des opinions d'un people sur le langage
et du langage sur les opinions?”). Mendelssohn takes issue both
with Rousseau's attempt to explain the origin of human language on the
basis of a description of the natural condition that human beings
share with other animals and with his neglect of any consideration of
the providential character of the development of language
(Gesammelte Schriften 6/2, p. 27). In these early writings on
language, Mendelssohn emphasizes the interdependence of language and
its development with the development of innate, divinely-endowed
capacities. These capacities include not only reason as the ability to
grasp conceptual connections and employ arbitrary signs
(Gesammelte Schriften 6/2, pp. 9f), but also — in
tandem with the development of rational capacities — the
capacity for compassionate interaction in familial and social
settings. Thus, on the one hand, the recurrence of auditory, visual,
and gesticular phenomena enables reason to signify phenomena bearing
no resemblance to them and, indeed, to do so in a way decidedly
different from how other animals instinctively employ natural,
imitative signs (Gesammelte Schriften 6/2, p. 10). In this
manner Mendelssohn underlines the interdependence of reason and
language, understood as the use of arbitrary signs. On the other
hand, language develops within a process that is social as well as
cognitive and the starting point for the investigation of its origins
is the family rather than the individual. Borrowing from Condillac
and challenging Rousseau's view of language as primarily a tool for
socialization, Mendelssohn writes: “The drive to social life is
equally innate in human beings and leads immediately to the occasion
for exercising the capacity for language”(Gesammelte
Schriften 6/2, p. 8).

In Jerusalem, toward the end of his career, Mendelssohn
returns to the subject of language in the context of articulating the
sense in which Judaism is — for good reasons — a religion
of the spoken rather than the written word, relying on an a living
tradition to transmit and interpret divine legislation. In this
context Mendelssohn again emphasizes the fundamentally social
character of language in the context of the performance of rituals,
while calling attention to both the feebleness of ostensive definition
and the fraught prospects for maintaining the same reference for words
over time. In the course of arguing that human reason does not need
supernatural revelation in order to recognize the eternal truths
indispensable to its happiness, Mendelssohn notes that Judaism relies,
not upon written phrases or formulations that are “established
forever, immutable,” but instead upon a “living tradition
passed on by oral instruction,” capable of keeping pace with
changing times and circumstances (Jerusalem (1983), p. 97f,
102f (translation slightly altered)/Gesammelte Schriften 8,
pp. 160, 168). Judaism is thus for Mendelssohn primarily a religion
of the spoken word precisely as a means of maintaining its relevance
to real life in changing, historical contexts and maintaining the
personal bonds and Jewish identity among its members.

Mendelssohn adds a further reason for insisting that Judaism is a
religion of the spoken word, precisely as a supernatural legislation
rather than a revealed religion. The constant attention paid to the
written word not only can isolate human beings from one another and
speculation from practice, but also can induce a kind of idolatry.
Frozen in time, the written word can become an idol itself, obscuring
the distinction between itself and what it is meant to signify (see
Freudenthal (2012), pp. 105-134).

In this connection Mendelssohn conjectures that written language
emerged in the course of the development of visible signs, beginning
with a form of synecdoche where a concrete object reawakens the
thought of a particular characteristic, e.g., a dog as a sign of
fidelity. While the move from these objects to images of them and
ultimately to hieroglyphics seems natural enough, Mendelssohn muses
that the transition from hieroglyphics to a written alphabet
“required a leap,” far beyond ordinary human powers
(Jerusalem (1983), p. 108/Gesammelte Schriften 8,
p. 174). Nonetheless, it is written language's hieroglyphic origins
that Mendelssohn credits with the potential for superstition,
idolatry, and speculative excess. Because hieroglyphic signs have no
prototype in nature, they provided potent material for superstition
and, indeed, Mendelssohn refers to the need for written signs as
“the first occasion [Veranlassung] for idolatry”
(Jerusalem (1983), p. 113 (translation slightly
altered)/Gesammelte Schriften 8, p. 179).

In the second chapter of Jerusalem, this general account of
language and its development figures prominently in an argument that
Judaism is a form of supernatural legislation rather than revelation.
By regarding language as primarily a living dialogue between persons,
Judaism does not lose sight of its communicative function for the sake
of thought. As a result, theory and speculation remain tied to
historical practice and concrete action. Not coincidentally, the
language of Judaism is primarily prescriptive rather than descriptive;
even its written prescriptions are “largely incomprehensible
without unwritten commentaries … transmitted by oral
instruction.” Hence, the use of language in Judaism — its
script and ceremonial laws — fends off the all too human
tendency to idolize the language itself.

The appeal to tradition (oral instruction) is necessary, Mendelssohn
adds, given the fact that, over the course of time, the laws
themselves become unintelligible “since no words or letters
retain their sense unchanged from one generation to the next”
(Jerusalem (1983), p. 128 (translation slightly
altered)/Gesammelte Schriften 8, p. 193). In chapter 1
of Jerusalem he makes a similar claim after noting (a) the
elusiveness of inner perceptions to the perceiver herself and (b) the
impossibility of two people using the same words to express the same
“inner perceptions” (Jerusalem (1983),
p. 66/Gesammelte Schriften 8, pp. 133f). Where the words in
question designate inner perceptions, there is no possibility of
ostensive definition, no more when uttered today than when uttered
ages ago. Indeed, in a passage that suggests both the inscrutability
and endless deferral of reference, Mendelssohn observes that
“words cannot be explained [erläutert]
by things. Instead, we must again have recourse to signs and
words and, ultimately, to metaphors” (Jerusalem (1983),
p. 66/Gesammelte Schriften 8, pp. 133f). Nonetheless,
Mendelssohn is more confident about words designating objects of
external perceptions and about the prospects for mutual understanding
in regard to them. Not incidentally, ceremonial law's ritualized
character calls for a recurrent context (including specific objects
and persons) available to external perception in the course of an
exchange between persons (including God). Notably, ‘you’
and ‘we’ take precedence over ‘I’ and
‘it’ in such contexts, as the living references of the
former indexicals enables one to refer effectively to oneself and to
things generally.

Thus, in Jerusalem Mendelssohn stresses the ritual and
performative character of language, thereby complementing his view of
the inextricability of language and a reason that tempers speculation
with common sense. The mature Mendelssohn, keenly aware of the perils
of ostension in determining reference, tempers the claims of
speculation with those of common sense and is more concerned with
bridging theory and practice in the rites of language than in the
claims of pure theory. Nor should it be forgotten that Mendelssohn's
recognition of language's basically ritualistic and empathic
character, as a springboard to reason, is rooted in what he regards as
the possibilities of Judaism.

Mendelssohn enjoyed, as noted at the outset, a lifelong friendship
with G. E. Lessing. In addition to their work as co-editors, Lessing
anonymously published Mendelssohn's earliest works and collaborated
with him on the piece: Pope, a Metaphysician! Through his
popular plays, his influential work as a dramaturg, and his stormy
public debates with orthodox Lutheran clergy, Lessing was a
particularly daunting and engaging spokesman for the German
Enlightenment, making him all the more dangerous to its opponents. His
final work, Nathan the Wiseman, fittingly portrays a Jewish
sage (presumably modeled on Mendelssohn) who makes a poignant plea for
tolerance by arguing that the differences among religions are
essentially matters of history and not reason. Along with Mendelssohn,
Lessing embraced the idea of a purely rational religion and would
endorse Mendelssohn's declaration: “My religion recognizes no
obligation to resolve doubt other than through rational means; and it
commands no mere faith in eternal truths” (Gesammelte
Schriften, Volume 3/2, p. 205). To pietists of the day, such
declarations were scandalous subterfuges of an Enlightenment project of
assimilating religion to natural reason. Mention has already been made
of Lavater's attempt to draw Mendelssohn into religious debate. While
Mendelssohn skillfully avoided that confrontation, he found himself
reluctantly unable to remain silent when, after Lessing's death, F. H.
Jacobi contended that Lessing embraced Spinoza's pantheism and thus
exemplified the Enlightenment's supposedly inevitable descent into
irreligion.

Following private correspondence with Jacobi on the issue and an
extended period when Jacobi (in personal straits at the time) did not
respond to his objections, Mendelssohn attempted to set the record
straight about Lessing's Spinozism in Morning Hours. Learning
of Mendelssohn's plans incensed Jacobi who expected to be consulted
first and who accordingly responded by publishing, without
Mendelssohn's consent, their correspondence — On the
Teaching of Spinoza in Letters to Mr. Moses Mendelssohn — a
month before the publication of Morning Hours. Distressed on
personal as well as intellectual levels by the controversy over his
departed friend's pantheism, Mendelssohn countered with a hastily
composed piece, To the Friends of Lessing: an Appendix to Mr.
Jacobi's Correspondence on the Teaching of Spinoza. According to
legend, so anxious was Mendelssohn to get the manuscript to the
publisher that, forgetting his overcoat on a bitterly cold New Year's
eve, he delivered the manuscript on foot to the publisher. That night
he came down with a cold from which he died four days later, prompting
his friends to charge Jacobi with responsibility for Mendelssohn's
death.

The sensationalist character of the controversy should not obscure the
substance and importance of Mendelssohn's debate with Jacobi. Jacobi
had contended that Spinozism is the only consistent position for a
metaphysics based upon reason alone and that the only solution to this
metaphysics so detrimental to religion and morality is a leap of
faith, that salto mortale that poor Lessing famously refused
to make. Mendelssohn counters Jacobi's first contention by attempting
to demonstrate the metaphysical inconsistency of Spinozism. He takes
aim at Jacobi's second contention by demonstrating how the
“purified Spinozism” or “refined pantheism”
embraced by Lessing is, in the end, only nominally different from
theism and thus a threat neither to religion nor to morality.

Mendelssohn's criticisms of Spinoza are discussed below but first the
complexity of his relationship to Spinoza should be noted. In his
first publication, Dialogues (1761) he argued that many of
Spinoza's views were compatible with “true philosophy and
religion.” In Mendelssohn's mind, Leibniz may have given that
“true philosophy” its sharpest formulation but in all
likelihood by deriving its central idea of a preestablished harmony
from Spinoza. Moreover, as Mendelssohn puts it, Spinoza does not so
much deny the distinctiveness of the actual world as construe it as it
is in the mind of God before the creation, existing only as a part of
God (Philosophical Writings, 102ff, 108ff). A quarter of a
century later, Mendelssohn recapitulates the latter argument as the
key to understanding a “purified” or “refined”
Spinozism that Lessing, at least in the realm of philosophical debate,
would not have dismissed out of hand.

Nevertheless, as noted above, part of his response to Jacobi
consists in demonstrating the shortcomings of Spinoza's philosophy. As
might be expected, he criticizes Spinoza's idea that there is only one,
infinite, and necessary substance. The idea is arbitrary, Mendelssohn
contends, since one can legitimately distinguish between what is
independent or self-standing (das Selbständige) and what
obtains or persists for itself (das Fürsichbestehende).
“Instead of proving that everything obtaining for itself is only one,
he [Spinoza] establishes in the end only that everything independent is
one. Instead of demonstrating that the entire aggregate of everything
finite constitutes a single self-standing substance, he merely shows
that this aggregate must depend upon the sole infinite substance”
(Gesammelte Schriften, 3/2, p. 107).

On a “deeper level,” as Mendelssohn puts it, he also takes
issue with Spinoza for failing to account for what Mendelssohn deems
the “formal” aspects of both corporeal and spiritual
worlds. Thus, Spinoza's conception of extension in terms of
impenetrability may explain “the essence of matter,” but
it leaves unexplained, Mendelssohn contends, the particular
organization and movement of bodies. What is unclear to Mendelssohn is
how parts can be in motion if the whole upon which they completely
depend (Spinoza's substance) is not in motion. Similarly, he wants to
know how, on the basis of Spinoza's account of the supposedly
underlying attribute of extension, those parts come to have the
particular form and organization of motions and forces that they have,
that is to say, as organic, self-regulating entities. “Where can
the origin of this [motion and form] be found?” he
asks. “Not in the whole, since the whole has no movement. The
sum [Sämmtliche] of all bodies, untied into a single
substance, cannot change place and has neither organization nor
figure…. Whence the form in the parts, if the whole provides
no source for this?” (Gesammelte Schriften, 3/2,
p. 108).

Just as Spinoza explains the matter but not the form of the physical
world, so, too, Mendelssohn charges, he gives an account of the matter
but not the form of the spiritual world. In this connection it is
helpful to recall Mendelssohn's differentiation of knowing, approving,
and desiring from one another. Truth and falsity, corresponding to
knowing, provide the matter of the spiritual world. While they may, as
Spinoza maintains, have their origin in thought as the attribute of a
single, infinite substance, categories corresponding not to knowledge
but to approving or desiring must have some other source. Thus,
according to Mendelssohn, Spinoza leaves unexplained “the difference
between good and evil, desirable and undesirable, pleasure and pain”
(Gesammelte Schriften, III/2, p. 109).

Yet, while some of these criticisms of Spinoza may be compelling, they
do not, Mendelssohn recognizes, carry the day for a refined Spinozist
or pantheist. Spinoza's inability to explain how movement and values
derive from the attributes of the one, infinite substance does not, by
itself, establish the theist explanation in Mendelssohn's
view. Accordingly, in Morning Hours he casts Lessing as the
spokesperson for a refined pantheism — a move that figures
prominently in this contribution to the Pantheismusstreit.
Lessing is portrayed as someone who, while agreeing with Mendelssohn's
theist position, has a knack for giving every reasonable argument its
full due. In this context Lessing presents a pantheism that
characterizes the one and only substance, not only as a source of
motion and desire, but also as capable of representing every
possibility to itself and approving that possibility that constitutes
“the best and most perfect series of things” (Morning
Hours, p. 84/Gesammelte Schriften 3/2, p. 115). In
other words, refined pantheism includes every aspect of the entire
metaphysical system of theism but casts it solely as the object of
divine intellect. As a result, a refined Spinozist might wonder how
different the positions are since the theist purports to explain these
seemingly recalcitrant phenomena merely by appealing to the divine
will. A refined pantheist might accept the difference between the
world (thought) and God (thinker) at a certain level, but insist that,
in the end, the difference is on a merely abstract level since
thinking and thought can only be distinguished as long as one is not
actually thinking. After all, “who is to tell us that we
ourselves and the world surrounding us have something more to them
than the thoughts of God and modifications of his original
power?” (Morning Hours, p. 84 (translation slightly
altered)/Gesammelte Schriften, 3/2, p. 116). To pretend to
show that there is something that can be predicated of things outside
God that cannot be predicated of the divine thoughts of those things
is to deny divine omniscience.

But, without further qualifications, this pantheist line of reasoning
is faulty, Mendelssohn submits, for at least three reasons. In the
first place, it abolishes a distinction presupposed by any truthful
statement, i.e., the distinction between original and copy. Secondly,
there are indefeasible marks that distinguish a finite
self-consciousness (as an object and original) from the divine
representation (copy) of it. “Consciousness of myself, combined
with complete ignorance of everything that does not fall within my
sphere of thinking, is the most telling proof of my substantiality
outside God, of my original existence” (Morning Hours,
p. 85 (translation slightly altered)/Gesammelte Schriften,
3/2, p. 118). Finally, the pantheist confuses divine knowledge with
divine approval. God knows perfectly well my shortcomings without
approving them and requiring their existence. Moreover, that they are
thinkable hardly explains their existence since the opposite of them
is just as thinkable. The problem for the pantheist, Mendelssohn
submits, is explaining their existence, i.e., explaining what
privileges some divine thoughts over others.

For the theist, by contrast, there is a ready solution to the
problem. “The thoughts of God that come to reality to the exclusion of
the rest will have this prerogative by virtue of their relative
goodness and purposiveness, insofar, namely, as they correspond thus
and not otherwise, here and now, to the idea of the perfect and best”
(Morning Hours, p. 89/Gesammelte Schriften 3/2, p. 122).

Still, the difference between the theist and a refined pantheist
is by no means this simple, Mendelssohn is quick to add. To be sure,
Spinoza conceived intellect and will as one and the
same. Nevertheless, at least as Lessing understood him, Spinoza also
differentiated acquaintance with what is true from acquaintance with
what is good and identified knowledge of the good with the
“will” insofar as through it one thought does have a
prerogative over another. Pantheism, so refined, secures religion and
morality no less than theism does, such that, assumning as much,
Mendelssohn is led to ask: “in what way now does the system
defended by my friend [Lessing] differ from ours?” (Morning
Hours, p. 89/Gesammelte Schriften, 3/2, p. 123). Seen in
this light, the difference between theism and refined pantheism turns
in the end on a speculative subtlety without practical consequences,
namely, on different interpretations of the metaphor of divine light.
Mendelssohn accordingly concludes that, like many another dispute in
metaphysics and epistemology, the dispute between refined pantheists
and traditional theists is purely verbal.

Gottlieb, Michah (ed.), 2011. Moses Mendelssohn: Writings on
Judaism, Christianity, and the Bible (The Tauber Institute Series
for the Study of European Jewry and the Brandeis Library of Modern
Jewish Thought). Curtis Bowman, Elias Sacks, and Allan Arkush
(trans.). Waltham, MA: Brandeis University.

DiGiovani, George, 1998. “Hume, Jacobi, and Common Sense: An
Episode in the Reception of Hume in Germany at the Time of Kant,”
Kant-Studien, 89(1): 44-58.

Falkenstein, Lorne, 1998. “A Double Edged Sword? Kant's Refutation
of Mendelssohn's Proof of the Immortality of the Soul and Its
Implications for His Theory of Matter,” Studies in the History and
Philosophy of Science, 29A(4): 561–88.

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